Arrangement for adjusting the blades of opposite rotating air propellers



Jan. 4, 1944. R. FREITAG ARRANGEMENT FOR ADJUSTING THE BLAD ES OF OPPOSITE ROTATING AIR PROPELLERS Filec} Oct. 20, 1939 9m n a T N T m w U V N V. cm I @J w 0 Y ..n -B a Patented Jan. 4, 1944 zssalizo.

OFFICE ARRANGEIHEN'T FOB ADJUSTING THE BLADES F OPPOSITE ROTATING AIR PBOPELLERS Reinhold Freitag, Stuttgart-Untertuerklielm,

Germany; vested in the Alien Property Custodlan Application October 20, 1939, Serial No. 300,334

Claims.

This invention relates to the adjustment of Germany October 13, 1938 (C1. ll-135.6.)

propeller blades for aircraft and, more particularly, to an arrangement for the adjusting of the pitch of two oppositely rotating propellers.

An object of this invention is to attain the application of a pitch adjusting force equally to two air propellers in such a manner that the blades are simultaneously adjusted. A further object is to make the adjustment of one blade dependent from the adjustment of the other. When providing for the adjustment of the blades of two propellers with the adjustment of one dependent upon the adjustment of the other, a fixed adjusting point or its equivalent must be provided between the two propellers. Such a fixed point may be provided by extending a lever from the motor casing through the center of the propeller nearest thereto, or a fixed member may be extended through the hollow propeller shaft. By extending a fixed lever through the center of the one propeller, the eiiiciency of the propeller is decreased and the construction is complicated. On the other hand, when a fixed member is extended through a hollow propeller shaft, the propeller shaft can no longer be used for the passage of shells or bullets as is desirable in modern warcraft.

In accordance with the present invention, these disadvantages are avoided by providing an artificially created fixed point from which the adjusting forces are transferred from one propeller to the next and thispoint has no fixed mechanical connection with the stationary parts of the airplane. Thus, the adjusting forces are transferred from one propeller to the next with the result that two or more propellers may be adjusted simultaneously.

In the illustrative embodiment of the invention, two oppositely rotating propellers are provided and, in the space between the propellers, a gear assembly is mounted which includes a plurality of gear wheels and two ring gears one of which is mounted on each propeller. Each of the gear wheels is mounted on a radial axis and meshes with both of the ring gears with the result that the opposite rotation of the propellers holds the gear wheels stationary. These stationary wheels provide a stationary support between the propellers. The entire gear assembly is mounted about the hollow propeller shaft which drives the propeller which is positioned remote from the driving motor. The gear assembly also includes lubricating means for lubricating the elements between the propellers. The blades of the propeller adjacent the driving motor are adto the other propeller.

justed by mechanism mounted on the motor casing, and the adjusting action is transferred through the gear assembly from this propeller Manual or automatic adjustment may be provided, depending upon the operating conditions.

In the drawing in which is shown one embodiment of the invention wherein two oppositely rotating airpropellers are driven by concentric hollow shafts:

Fig. 1 is a sectional view along the line ABC of Fig. 2; and,

Fig. 2 is an enlarged sectional view along the line DE of Fig. 1.

Referring particularly to Fig. 1, two propellers having blades l3 and M, respectively, are mounted upon two concentric hollow shafts 2 and 3, respectively. As shown, at the right hand side of the figure, a motor shaft l carries two gears 4 and 6 which are keyed to the shaft. Gear 4 drives shaft 3 through a gear 5 keyed to the shaft, and gear 6 drives shaft 2 through a reversing gear I and a gear 8 keyed to the shaft. A casing 9 encloses the gears and also carries a pitch adjusting assembly which includes a gear wheel II to which the adjusting action is applied by mechanism not shown. Gear wheel I I meshes with a ring gear [2 which has integral therewith a ring gear Ill. Each of blades I3 is mounted adjacent gear 10 in a boss l5 (see Fig. 2) upon a pair of roller-bearing units. The pitch of each blade I3 is controlled by a worm gear 33 mounted on a shaft 34 and meshing with a. worm wheel 35 fixed to the shaft 36 of the blade. Mounted upon each of shafts 34 and meshing with gear in is a gear ll. Normally, gear l0 rotates with the blades l3 but when an adjusting movement is transmitted to gear wheel ll, gear III is moved relative to the blades. This relative movement rotates gears I1 and in turn changes the pitch of each of the. blades through its shaft 34, worm 33 and worm wheel 35.

Referring to the left hand side of boss l5,

the boss has a sleeve-like ring gear I5 which tween the opposed ends of ring gears l5 and IS in an annular groove 3| in shaft 3 is a ring bearing 32. This ring bearing carries the inner ends of a plurality of radially extending shafts 20, the outer ends of which are carried by a casing 21. Mounted upon each of shafts 20 is a pinion gear 24 which meshes with both of the ring gears I5 and I8. As indicated above, the two propellers are rotated oppositely with the result that ring gears l6 and I6 move at the same speed in opposite directions past the opposite sides of gears 24. This maintains gears 24 stationary and also holds their shafts 20, ring bearing 22 and shell 21 stationary.

The pitch of blades I4 is controlled in the same manner as is the pitch of blades l3 with a gear |9, corresponding to gear I'I, transmitting the adiusting movement to each of the blades. Surrounding ring gear I5 is a ring gear 25 which has a gear portion meshing with a plurality of gears 2| mounted on shaft 20. Ring gear 25 also meshes with gears l8 one of which is mounted on the end of each shaft 34. Corresponding to gear 25 is a ring gear 26 which also meshes with gears 2| and has a gear portion meshing with adjusting gears I9. Thus, an adjusting movement of gears I1 is transmitted through shafts 34, gears I8, 25, 2|, 26 and I9 to blades l4. However, when there is no adjusting movement, ring gears 25 and 26 rotate about gears 2| at the opposite sides thereof in opposite directions at the same rate so that gears 2| rotate but there is no adjustment of the blade pitch.

In the bottom of casing 21, a lubrication unit is provided with the lubricant being collected in an oil sump 28 and passed by an impeller 23 through a conduit 29 to a central bore 30 in the hollow shaft 20. From the top of hollow shaft 20, the oil is distributed to the ring bearing and the other elements within casing 21. The oil then returns to sump 28.

During operation, the opposite rotation of ring gears l5 and Hi maintains gears 24 stationary in an angular sense, and thus holds casing 21 and its associated parts in a fixed position. Thus, a fixed point is created from which the adjusting forces are transmitted from the propeller blades l3 to the propeller blades l4.

The number of blades in each propeller may be varied and the number of propellers may be ining a hub and blades, the latter being rotatably mounted in said hub, a plurality of shafts, a propeller keyed to each shaft, said shafts being concentrically arranged, means to revolve adjacent shafts in opposite directions to each other, a gear on each hub, a conical gear between each pair of adjacent propellers in mesh with said hub gears, an adjusting gear on each blade to rotate the same, and a reversing gear associated with each of said conical gears, and in operative engagement with the said adjusting gears on the blades of adjacent propellers, and actuating means laterally disposed to said propellers to rotate the adjusting gears on the blades adjacent to said actuating means, whereby the pitch of all blades is simultaneously adjusted.

2. The device claimed in claim 1, comprising a lubricant conveying means for said hub gears, said conveying means being connected to said reversing gear for operation thereby.

3. The device claimed in claim 1, which comprises a gear casing between each pair of propellers, a spindle supporting each conical gear and associated reversing gear, each spindle being mounted at one end in a stationary ring surrounding the respective supporting shaft and at the other end in said gear casing.

4. In an aircraft having propeller blades with adjustable pitch, a plurality of co-axially disposed oppositely rotatable air propellers with adjustable blades, supporting means for said propellers, the latter being mounted on said supporting means at spaced points, gear means provided on each blade on the outside of said supporting means, a reversing gear disposed between adjacent propellers and operatively connected to the gear means of the blades thereof, said reversing gear being disposed outside of said supporting means, and actuating means connected to said gear means for simultaneously adjusting the pitch of the propeller blades, whereby due to said reversing gear the blades of oppositely rotating propellers are turned in opposite directions, said actuating means consisting of an actuating gear, a transmitting gear connected to each gear means of the blades adjacent said actuating gear, the latter meshing with said transmitting gears.

5. A device as claimed in claim 4 which also includes an automatically operated control device operatively connected to said actuating gear to control the same.

REINHOLD FREITAG. 

